The problem is not with "acting", provided the acting has a godly purpose. For instance, some of the prophets used "acting" to convey the Lord's message (e.g., 1Kings 20:35-43, Ezekiel 4:1-17).
However, most movies are dishonoring to God and promote sin. Christians should have nothing to do with ungodly movies that promote sensuality, foolish talk, pride, greed, occult practices, stealing, crime, violence, worldliness, etc. Remember that because of these things, the wrath of God is coming.(Colossians 3:6) It is shameful even to mention what the disobedient do in secret.(Ephesians 5:11-12)
On another note, you may want to listen to Zac Poonen's take on the word "actor" - https://www.sermonindex.net/modules/mydownloads/visit.php?lid=4272
In Christ,
Renoncer